tools: Added etcd_init.sh

[ashcrow]

Created the tools directory to house non-required yet helpful tools we may want to provide along with the service code. etcd_init.sh is the first tool added which initializes the Commissaire etcd keyspace.

Issue originally found by @gbraad while installing commissaire-storage-service for the first time.

[mbarnes]

Oh hey, good timing! You know what else this script could do is make sure there's an entry for the default cluster network (as in C.DEFAULT_CLUSTER_NETWORK_JSON) so that storage lookups don't require a special case. I hacked that into the investigator service but this is clearly a better place for it.

I'll do a proper review in the morning.

[ashcrow]

👍 will add hopefully before standup this morning.

[ashcrow]

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[mbarnes]

I learned from Colin to always add set -euo pipefail at the beginning of bash scripts so it fails on error the way you would expect a program to. Otherwise looks and works great!

Update: Actually if you do add that, also append || true to the etcdctl mkdir line so the script doesn't abort over the key existing already.

(see: http://redsymbol.net/articles/unofficial-bash-strict-mode/)

[ashcrow]

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